1. Field of the Invention
The invention relates generally to mechanisms for ejecting payloads from a spacecraft and more particularly to mechanisms for ejecting payloads ejected with translational and rotational motion from a spacecraft.
2. Description of the Related Art
Commonly assigned U.S. Pat. No. 4,359,201 describes an arrangement for launching a payload with translational and rotational motion from a spacecraft. The arrangement comprises a U-shaped or open-ended cradle, and a payload with at least one attachment member on one side thereof and at least two attachment members in longitudinally spaced positions on an opposite side thereof. The payload straddles the open end of the cradle, and the attachment members releasably engage the cradle and support the payload in the open end of the cradle. The attachment members define corners of a triangle which encloses the center of mass of the payload. An ejection mechanism having a part disposed between the cradle and the one attachment member applies a tangential ejection force to one side of the payload at the location of the one attachment member to eject the payload with translational and rotational motion.
Commonly assigned U.S. Pat. No. 4,303,214 discloses a similar arrangement and describes an ejection mechanism in greater detail. The ejection mechanism described therein comprises a plurality of helical coil springs which drive a push rod which extends upward from the mechanism and engages a fitting comprising a portion of the payload. During payload ejection, the spring-driven push rod imparts an ejection force to the fitting in a direction toward the open end of the U-shaped cradle.
While earlier ejection mechanisms generally have been satisfactory, there have been shortcomings with their use. More particularly, the simultaneous translational and rotational motion of the payload during ejection resulted in frictional energy loss as the push rod slid along the surface of the fitting during payload ejection. This frictional loss resulted in undesirable effects on the motion of the payload.
Thus, a need exists for an ejection mechanism which provides a tangential ejection force to a payload ejected with translational and rotational motion from a spacecraft and which provides such an ejection force without introducing unwanted frictional energy loss. The present invention meets this need.